Oil heater



A ril 18, 1961 w. H. THOMPSON OIL HEATER Filed 001;. 14, 1959 n Z6 S mm W E T N N R E 0 W n m J 0v WW OIL HEATER William H. Thompson, Chatham, N.J., assignor to American Metal Products Company (Davis Engineering DlVlsion), Elizabeth, N.J., a corporation of Michigan Filed Oct. 14, 1959, Ser. No. 846,392

12 Claims. (Cl. 15836) The present invention relates to oil heaters of the general type adapted for use in connection with the pumping of viscous fuel oils, for example, and more particularly to a novel oil heater of generally simplified design and improved operating characteristics.

In connection with the storage and delivery of viscous fuel oils, for example, it is conventional to provide in a relatively large storage tank a heater associated with the output or suction line, so that the temperature of the oil is raised and its viscosity lowered before it enters the delivery system. The present invention relates to an improved form of a heater of this general type, the improved heater being adapted particularly for use in connection with horizontal, underground storage tanks, for example.

One of the improved features of the new heater resides in its substantial overall simplicity, providing for economy in manufacture and substantial facility of maintenance and repair. In accordance with one of the specific aspects of the invention, the new heater comprises a tube which extends vertically into the storage tank and is exposed at its lower end to the oil supply. A heat exchange element is housed within the heating tube, and oil flowing upwardly through the tube to a delivery or suction line is heated and rendered less viscous in the desired manner. The overall arrangement of the components of the heater is such that the heat exchange element may be removed easily from time to time, for inspection or maintenance, regardless of the level of the oil in the tank.

Another specific feature of the invention resides in the provision of a heater having a vertical tube exposed to the lower portion of a supply tank and having an enlarged mixing bell surrounding the lower end of the tube and projecting somewhat below it. The mixing bell receives partially heated oil being returned from the external oil system, mixes it with cold oil from the tank and causes the mixture to be directed into the lower end of the tube. In this manner, maximum heating efliciency is realized. A simplified and highly practical arrangement for discharging air from the oil system is also incorporated as part of the heater and comprises a discharge or vent tube opening into the top of the mixing bell and extending upward above the level of the oil in the tank.

The new heater, while providing many advantageous operating characteristics, is highly simplified in its structural arrangement, so as to be relatively small in physical size, inexpensively fabricated, easily installed in and/or removed from an oil supply tank, and capable of economical maintenance.

For a better understanding of the above and other advantageous features of the invention, reference should be made to the following detailed specification and to the accompanying drawing, in which:

Fig. l is a representative elevational view, partly in section, of an underground, horizontal supply tank incorporating a heater according to the invention;

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Fig. 2 is an enlarged, elevational view, partly in section, of the heater of the invention;

Fig. 3 is a top view of the heater of Fig. 2; and

Fig. 4 is a fragmentary, cross-sectional view of a modified form of the heater of Fig. 2.

Referring now to the drawing, the reference numeral 10 designates generally a storage tank for oil or the like which is generally horizontally disposed and located below ground level 11. Near one end, the tank has a vertical extension 12 provided with a flange 13 located at or somewhat above the ground level. The vertical extension 12 forms an access opening into the interior of the tank.

In accordance with the invention, the new heater is mounted on the flange 13 and extends vertically downward into the tank, the lower end of the heater lying adjacent to but spaced somewhat (e.g., six inches) above the bottom wall 14 of the tank. For mounting the heater there is provided a mounting plate 15 of a suitable size and shape to be supported on the flanges 13 and closing off the access opening to the tank. Suitable bolts 16 or other means are provided for securing the mounting plate 15 to the tank flanges 13.

Mounted rigidly on the plate 15, as by welding at 17, is an elongated tube, sometimes referred to as a containing tube, which is in the form of a pipe of an appropriate diameter (e.g., six inches), and it houses heat exchange tubes 34, 35, or coils 43, 44, which are of suitable proportions to produce the desired heating capacity. A portion of the containing tube extends upward above the mounting plate 15 and has fixed thereto a mounting flange 19. The upper portion of the tube is also provided with an outlet pipe connection 20 located below the mounting flange 19 and above the maximum liquid level in the tank. The lower portion of the tube 18 extends downward and is in open communication with the tank at a point spaced somewhat (e.g., eight inches) above the bottom wall 14 of the tank. The outlet connection 20 may be a conventional pipe fitting, for example, and is adapted for connection to a suction line 21 leading to a pump 22. The pressure line 23 of the pump conventionally would lead to a by-pass valve 24, which directs the oil at predetermined pressure into a burner 25, for example, and returns the excess through a return line 26.

Mounted at the lower end of the tube 18 is a mixing bell 27, which advantageously is in the form of a relatively large diameter cylindrical pipe section. In accordance with one aspect of the invention, the lower end of the mixing bell extends below the lower end of the tube 18 and is open to the interior of the tank. The upper end of the mixing bell is closed off by a cover plate 28. Advantageously, the mixing bell 27 is mounted in eccentric or oifset relation to the containing tube 18, so that the extreme lower end of the containing tube projects into the mixing bell at one side thereof, substantially as shown in Fig. 2.

Secured at its upper end by the mounting plate 15 and at its lower end by the top plate 28 of the mixing bell is an oil return tube 29 which extends generally vertically in the tank and is in open communication with the upper portion of the mixing bell. Advantageously, the return tube i mounted at its upper end by means of a connector 30, to which a pipe 31, forming part of the return line 26, may be connected. The connector 30 may be rigidly secured to the plate 15 as by welding at 31'.

An air vent or discharge tube advantageously is mounted at its lower end by the plate 28 of the mixing bell, in open communication with the upper portion of the bell, and extends generally vertically upward along the tube 18, advantageously to a point just below the mounting plate 15. The upper end of the air discharge tube 32 is open to the atmosphere within the tank but above the level thereof which the oil will assume when the tank is filled. Advantageously, the upper end of the air discharge tube is tack-welded to the side of the tube 18, substantially as indicated at 33.

Received within the containing tube 18 is a heat exchange element or unit, generally designated by the numeral 34-, which extends substantially throughout the tube. In the form of the invention illustrated in Fig. 2, the heat exchange unit comprises a plurality of U-shaped tubes 35 supported at their upper ends by a tube sheet 36, the upper ends of the tubes being exposed at the top of the tube sheet.

Mounted above the tube sheet 36 is a cap 37, which is bolted to the flanged fitting 19 at the top of the tube 18 and serves to hold the tube sheet and tubes 35 in place in the assembly. Suitable bolts 38 extend through the cap, tube sheet and flanged fitting 19 to maintain the parts in assembled relation, substantially as shown in Fig. 2.

In the illustrated form of the invention, the cap 37 is provided with two fittings receiving pipes 39, 40 for delivering and carrying away a heat exchange medium, such as hot water. The heat exchange medium is delivered through the pipe 39, for example, and enters a chamber 41 over the left hand side of the tube sheet 36. The medium thus enters one end of each of the U-shaped tubes, travel through the tubes and is discharged into a chamber 42 above the right hand side of the tube sheet. The medium then flows from the chamber 42 out through the pipe 40.

In some instances, it may be desirable to use a heating medium such as steam, in which case it may be desirable or expedient to use a modified form of heat exchange element, such as shown generally at 43 in Fig. 4. The modified heat exchange element may comprise a continuous coil extending from the top of the tube 18 to a point near the bottom of the tube and then substantially directly upward again to the top of the tube. The incoming steam may be flowed through the coil 44 first, to provide a countercurrent heat exchange relationship.

In the operation of the new heating device, the device is mounted vertically in the tank 10, as shown in Fig. 1, the tank being at least partially filled with a viscous liquid medium, such as fuel oil. Heat exchange medium is introduced into the heat exchange element 34 through the pipes 39, 40, to heat the oil within the tube 18, rendering the oil less viscous. When the oil is in a flowable condition, the pump 22 may be started to deliver the oil through a by-pass valve 24 to a consumption unit 25. Some of the oil is by-passed by the valve 24 and flows through the return line 26 and into the return tube 29 of the heating device. The returning, heated oil flows downward through the return tube 29 and into the upper portion of the mixing bell 27. Naturally, the rate of return flow through the tube 29 is less than the rate of outflow through the tube 18, since some of the oil is consumed at the unit 25. Accordingly, there is a net flow of oil from the tank, into the mixing bell and tube 18. The cold oil flowing from the tank into the mixing bell meets with the downward flowing, heated oil discharged from the return tube 29, and a certain amount of mixing occurs as the two streams of oil meet. Accordingly, the net flow of oil toward the open end of the tube 18 is made up of a partially heated body of oil. This simultaneously facilitates the entry flow of oil into the lower end of the tube 18 and effects a substantial conservation of the heat of the returning oil. In this respect, it will be observed that the return tube 29 is of relatively small diameter, consistent with proper flow conditions, so that heat exchange through the walls of the return tube to the general body of cold oil is minimized.

As the partially heated oil flows into and up through the tube 18, it is heated substantially by the heat exchange unit 34, and the viscosity of the oil is reduced substantially to facilitate its flow to the consumption unit under the action of the pump 22.

During the circulation of the oil through the system, it may be expected that a certain amount of air will become entrained in the flowing streams. Entrapment of some or all of this air within the mixing bell 27 and/or tube 13 may result in a substantial reduction in the efliciency of operation of the heating device. It could also interfere with the operation of the oil burner by interrupting a continuous flow of oil to the burner, finally resulting in blowing out of the flame. Accordingly, the lower end of the air discharge tube 32 is located adjacent the discharge end of the return tube 29, at the top of the mixing bell. Air being carried into the hell with the returning oil tends to collect in the top of the bell which, as illustrated particularly in Fig. 2, is a substantial distance (e.g., eight inches) above the lower and of the tube 18. The air collecting in the top portion of the mixing bell eventually finds its way to the air discharge tube 32 and travels upward through the tube to be discharged at the upper end thereof. As will be under stood, the upper end of the discharge tube 32 at all times lies above the top level of the oil in the tank, so that the air is simply discharged into the top area of the tank. One of the advantageous features of the specific air discharge arrangement of the invention is that it does not result in the loss of a portion of the returning, heated oil to the general body of cold oil in the tank.

It is usually necessary to remove the heat exchange unit 34 from time to time for cleaning of the heat exchange tubes, whose outer surfaces may become encrusted with deposits of material of low heat exchange efficiency. As one of the advantageous features of the invention, the entire heat exchange unit 34 may be removed bodily by removing the bolts 38 and lifting the entire unit out of the tube 18. It will be understood that such removal of the heat exchange element may be effected regardless of the level of the oil in the tank 10, since the upper end of the tube 18 is well above the maximum level of the oil in the tank. Of course, certain parts of the circulation system may lie above the upper end of the heating tube, in which case suitable valves 45, 46 may be provided in the suction line 21 and return line 26, and these valves may be closed off during the removal of the heat exchange unit.

The new heating device has significant advantages in respect of its overall simplicity and ease of installation and maintenance. In addition, the various structural advantages of the new heating unit are combined in such a way as to provide a heater of improved overall operating efiiciency and substantial heating capacity in relation to its physical bulk.

It should be understood that the forms of the invention herein specifically illustrated and described are intended to be representative only, as certain changes may be made therein without departing from the clear teachings of the disclosure. Accordingly, reference should be made to the following appended claims in determining the full scope of the invention.

I claim:

1. An oil heater for mounting on a wall of an oil tank, comprising a containing tube extending generally vertically into the tank and terminating above the bottom wall thereof, a mixing bell mounted at the lower end of the containing tube and having walls surrounding the open end of the containing tube, said mixing bell being substantially closed at its top and having an open lower end spaced above the bottom wall of the tank, the lower end of said containing tube extending substantially below the top wall of said mixing bell but terminating above the lower edge of the walls thereof, an oil return tube extending generally vertically into the tank and having its lower end open to the interior of the mixing bell, an air discharge tube extending generally vertically in the tank and having its lower end open to the upper portion of the mixing bell and its upper end terminating within the tank above the oil level therein and open to the atmosphere, heat transfer means mounted at the top of and extending downward into the containing tube, and means adjacent the top of the tube for connecting an oil output line.

2. The oil heater of claim 1, in which a mounting plate is secured to the containing tube near its upper end, the upper end of the oil return tube extends through said plate, and the air discharge tube has its open upper end exposed below the plate but closely adjacent thereto.

3. The oil heater of claim 1, in which the mixing bell is mounted in ofiset relation to the containing tube, and the oil return and air discharge tubes are secured at their lower ends to the offset portion of the bell.

4. The oil heater of claim 1, in which the vertical dimension of the mixing bell is small in relation to that of the containing tube, and the lower end of the mixing bell lies between the lower end of the containing tube and the bottom wall of the tank.

5. The oil heater of claim 1, in which the heat exchange means comprises tube means for conveying a fluid heat exchange medium, a tube sheet engages the upper ends of the tube means, a flange is mounted at the upper end of the containing tube to support the tube sheet, a cap is secured to the tube sheet and flange to retain the tube sheet in position on the flange, and means are provided in the cap to connect delivery and return lines for heat exchange medium.

6. The oil heater of claim 1, in which the heat exchange means is mounted removably at the upper end of the containing tube, and the means for connecting an oil output line are disposed below the upper end of the containing tube and above the top of the tank. I

7. The oil heater of claim 1, in which the air discharge tube is secured at its lower end to the upper wall of the mixing bell and at its upper end to the side wall of the containing tube.

8. An oil heater for mounting on a wall of an oil tank, comprising a tube extending generally vertically into the tank and terminating above the bottom wall thereof, a mixing bell mounted at the lower end of the tube, and having walls surrounding the open lower end of the tube, said mixing bell being substantially closed at its top and having an open lower end spaced above the bottom wall of the tank, the lower end of said containing tube extending substantially below the top wall of said mixing hell but terminating above the lower edge of the walls thereof, a return tube for heated oil extending generally vertically into the tank and having its lower end open to the interior of the mixing bell, an air discharge tube extendtng generally vertically in the tank and having its lower end open to the upper portion of the mixing bell and its upper end terminating within the tank above the oil level therein and open to the atmosphere, and means adjacent the top of the tube for connecting an oil output line.

9. The oil heater of claim 8, in which a mounting plate is secured to the tube near its upper end, the upper end of the oil return tube extends through said plate, and the air discharge tube has its open upper end exposed below the plate but closely adjacent thereto.

10. The oil heater of claim 8, in which the mixing bell is mounted in offset relation to the tube, and the oil return and air discharge tubes are secured at their lower ends to the offset portion of the bell.

11. The oil heater of claim 8, in which the vertical dimension of the mixing bell is small in relation to that of the tube, and the lower end of the mixing bell lies between the lower end of the tube and the bottom wall of the tank.

12. The oil heater of claim 8, in which the air discharge tube is secured at its lower end to the upper wall of the mixing bell and at its upper end to the side Wall of the tube.

References Cited in the file of this patent UNITED STATES PATENTS 2,378,184 Carlson June 12, 1945 2,802,520 Trabilcy Aug. 13, 1957 FOREIGN PATENTS 973,376 France Sept. 13, 1950 

